Gareth,
I've calculated that I get about 1 to 3 "good" astronomy shots per roll
of film, on average. I've been doing astro stuff for a couple of years
now, and my success rate is improving, at least.
I'm using 800 film on the planets because of the need to get as short an
exposure as possible. The reason is that the planets are in in the part
of the sky where they move the "fastest". On my negatives the stars &
planets are "trailed" even at 8 second exposures with a 50mm lens (wider
lenses can go longer). Normally I shoot Kodak LE 400 (formerly PJ400)
for astro shots, and if it have another clear night and run out of 800
that's what I'll go with.
Skyglow and/or light pollution is almost always green in my experience.
The few astro slides I've taken show this clearly.
The green in the center of the pic is due to one or all of: skyglow at
twilight, light pollution, maybe the zodiacal light, and vignetting of
the camera lens. I partially corrected the green in photoshop, and given
enough time there is much more that could be done to the shot ;-) I kind
of like all the colors, though!
Don't get much aurora down here in Houston, TX ;-)
-Dick
p.s. links to astro & other pix at my home page:
http://home.houston.rr.com/dtlocke/index.html
I think most people would argue that sky glow is not green. An
exception might be an area with a lot of sodium vapor street lighting
which is rare these days. How a film represents it is another matter.
There is the matter of reciprocity failure which is different for
each layer with long exposure times. Plus there is a tendency of
different film formulations to have blacks of different shades. Years
ago one of the things I hated about Agfachrome, an otherwise pleasing
film, was that underexposure went to green, unlike the Kodak chrome
formulations which at the time went to blue or purple. Different film
formulations might yield different sky glow results.
I hesitated to respond after seeing your site. Stunning astro
photos. Nice equipment too.
--
Winsor Crosby
Long Beach, California
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